A Japanese Patent Application laid open No, JP-H09-304661A has disclosed a method to produce a bi-directional optical module, where the method includes a step to assemble an optical ferrule and a sleeve with an intermediate product of the optical module that installs a semiconductor Laser Diode (LD). The process practically activates the LD and detects optical power of an optical beam output from the LD by, for instance, a power meter as an electrical signal. The method compares thus obtained electrical signal with a preset value, and aligns the optical ferrule within a plane perpendicular to an optical axis of the optical module, and the position of the sleeve, into which the optical ferrule is inserted.
When an optical module assembles with optical components such as an optical ferrule, the optical components are necessary to be aligned with a semiconductor optical element installed within the optical module. However, the optical module itself generally assembles various parts, such as a cap having a lens and/or a stem mounting the semiconductor optical element thereon, where the cap and the stem constitute an optical device that encloses the semiconductor optical element therein. Accordingly, when an optical sleeve that is to receive an external optical ferrule secured in an end of an external optical fiber to be optically coupled with the semiconductor device is to be fixed with the cap of optical device, the cap is not always precisely aligned with the semiconductor optical element mounted on the stem. That is, the cap is not always precisely aligned with the stem, in particular, the cap is sometimes fixed to the stem with an inclined angle. Accordingly, the in order to precisely align the sleeve with the cap, the cap is necessary to precisely head on the sleeve to be fixed.